Blockchain-implemented method and system

ABSTRACT

The invention provide a blockchain-implemented control method and corresponding system(s). The invention may be arranged to control access to and/or use of an interne-enabled resource such as for example an IoT device. The resource may be a device or system. It may, for example, be a vehicle such as a driverless taxi or car. The vehicle may be provided with computing capabilities to enable it to communicate with other computer-based resources and/or interact with a distributed ledger. This distributed ledger may be a blockchain, such as, for example, the Bitcoin blockchain. In one embodiment, the invention provides a method for controlling the use of an interne-enabled resource comprising the steps of: providing a first blockchain transaction comprising at least one output which is redeemable only by provision of at least: i) a secret value selected by a user; and ii) a signature associated with a resource provider; sending use-related information to the resource; generating a second blockchain transaction requesting at least the secret value; and modifying the second blockchain transaction to include the secret value.

This invention relates generally to distributed ledger technology (including blockchain related technologies), and in particular for access to and use of a controlled resource via the blockchain. The invention is particularly suited for providing a secure system for enabling the access to and/or use of the resource. Aspects of the invention relate also to the Internet of Things (IoT). The invention may be suited for controlling an IoT device.

In this document we use the term ‘blockchain’ for the sake of convenience and ease of reference because it is currently the most widely known term in this context. The term is used herein to include all forms of electronic, computer-based distributed ledgers, including consensus-based blockchains, alt-chains, sidechains and transaction-chain technologies, public or private, permissioned and un-permissioned ledgers, private or public ledgers, shared ledgers and variations thereof.

A blockchain is an electronic ledger which is implemented as a computer-based decentralised, distributed system made up of blocks which in turn are made up of transactions. Each transaction includes at least one input and at least one output. Each block contains a hash of the previous block to that blocks become chained together to create a permanent, unalterable record of all transactions which have been written to the blockchain since its inception. Transactions contain small programs known as scripts embedded into their inputs and outputs, which specify how and by whom the outputs of the transactions can be accessed. On the Bitcoin platform, these scripts are written using a stack-based scripting language.

In order for a transaction to be written to the blockchain, it must be i) validated by the first node that receives the transaction—if the transaction is validated, the node relays it to the other nodes in the network; and ii) added to a new block built by a miner; and iii) mined, i.e. added to the public ledger of past transactions.

The most widely known application of blockchain technology is the Bitcoin ledger, although other blockchain implementations have been proposed and developed. While Bitcoin may be referred to herein for the purpose of convenience and illustration, it should be noted that the invention is not limited to use with the Bitcoin blockchain and alternative blockchain implementations fall within the scope of the invention.

Blockchain technology is most widely known for the use of cryptocurrency implementation. However, in more recent times, digital entrepreneurs have begun exploring both the use of the cryptographic security system Bitcoin is based on, and the data that can be stored on the Blockchain, to implement new systems.

One area of current interest and research is the use of the blockchain for the implementation of “smart contracts”. These are computer programs designed to automate the execution of the terms of a contract or agreement. Unlike a traditional contract which would be written in natural language, a smart contract is a machine executable program which comprises rules that can process inputs in order to produce results, which can then cause actions to be performed dependent upon those results.

Another area of blockchain-related interest is the use of ‘tokens’ (or ‘coloured coins’) to represent and transfer real-world entities via the blockchain. A potentially sensitive or secret item can be represented by the token, which has no discernable meaning or value. The token thus serves as an identifier that allows the real-world item to be referenced.

The invention also relates to the use of a blockchain-implemented mechanism to control access to a resource. This resource can be an “internet of things (IoT)” device. IoT has been described by Wikipedia as “the network of physical devices, vehicles, buildings and other items embedded with electronics, software, sensors, and network connectivity that enables these objects to collect and exchange data . . . The IoT allows objects to be sensed and controlled remotely across existing network infrastructure”.

The present invention is defined in the appended claims.

The invention may provide a blockchain-implemented control method and corresponding system(s). The invention may be arranged to control access to and/or use of an internet-enabled resource. The resource may be a device or system. It may, for example, be a vehicle. The vehicle may be provided with computing capabilities to enable it to communicate with other computer-based resources and/or interact with a distributed ledger. This distributed ledger may be a blockchain, such as, for example, the Bitcoin blockchain.

The invention may provide a method comprising the steps of:

-   -   providing a first blockchain transaction comprising at least one         output which is     -   redeemable only by provision of at least:         -   a secret value selected by a user; and         -   a signature associated with a resource (e.g. vehicle)             provider;     -   sending use (e.g. journey) related information to the vehicle;     -   generating a second blockchain transaction requesting at least         the secret value; and     -   modifying the second blockchain transaction to include the         secret value.

By providing the above-described method, provision and use of a controlled resource (e.g. driverless vehicle) is enabled having the advantages of secure payment and tamper-proof record-keeping of transactions.

The use (e.g. journey) related information may be sent by the resource/vehicle provider in the form of a tokenised third blockchain transaction comprising either the information or a pointer thereto.

This provides the advantage of preventing third parties from accessing the information.

The method may further comprise a step of generating a fourth blockchain transaction comprising at least one output redeemable to return an amount of cryptocurrency underlying the tokenised third blockchain transaction to the resource/vehicle provider.

This enables the vehicle provider to regain the underlying cryptocurrency, providing the advantage of making provision of the resource/vehicle more cost-effective.

The second blockchain transaction may be generated by the resource/vehicle and the modification may be performed by the user.

This provides the advantage of increasing the automation and the efficiency of the invention.

The second blockchain transaction may comprise a first output relating to an amount payable to the resource/vehicle provider or controller, and a second output relating to an amount repayable to the user.

This enables part of the deposit to be returned to the user of the invention as change, thereby providing the advantage of increasing the user-friendliness of the technique.

The second blockchain transaction may comprise preventing means for preventing at least one output of the second blockchain transaction from being modified by the user.

This provides the advantage of increasing the security associated with the invention.

The preventing means may take the form of a securing input to the second blockchain transaction comprising the sighash flag SIGHASH_ALL|SIGHASH_ANYONECANPAY.

This enables prevention of the outputs of the transaction from being modified while allowing modification of the inputs, thereby providing the advantage of increasing the security of the payment.

The securing input may comprise an amount of cryptocurrency provided by at least one of the vehicle provider and an electronic wallet associated with the resource/vehicle.

This provides the advantage of increasing the automation of the invention.

The method may further comprise a step of generating a fifth blockchain transaction comprising at least one output redeemable to refund an amount of cryptocurrency associated with the first blockchain transaction responsive to non-use of the resource/vehicle.

This provides a mechanism for allowing a refund of at least part of the deposit when a user of the invention decides to cancel their use of the resource, thereby providing the advantage of further increasing the user-friendliness of the invention.

The method may further comprise the step of unlocking the resource/vehicle in response to validation of modification of the second blockchain transaction.

This provides the advantage of further increasing the security of the invention.

The method may further comprise the step of a user of the resource sending at least one confirmation message confirming accuracy of the use-related information, hashing said message and storing said hashed message in a distributed hash table.

The method may further comprise the step of hashing the use-related information and storing said hashed information in a distributed hash table.

These provide the advantage of providing a simple and tamper-proof mechanism for recording the communications and their content for potential future reference.

The method may further comprise the step of determining a number of users present in, or using, the resource and allowing or disallowing provision of the resource dependent on said number.

This provides the advantage of preventing advantage being taken of the invention.

The resource may be a vehicle, which may be a driverless car.

This provides the advantage of a driverless taxi service capable of providing secure payment mechanisms and tamper-proof record-keeping of transactions.

These and other aspects of the present invention will be apparent from, and elucidated with reference to, the embodiment described herein. An embodiment of the present invention will now be described, by way of example only, and with reference to the accompany drawings, in which:

FIG. 1 shows a blockchain transaction adapted to provide a deposit payment for provision of a vehicle;

FIG. 2 shows a blockchain transaction adapted to communicate journey-related information;

FIG. 3 shows a blockchain transaction adapted to repay a vehicle provider;

FIGS. 4a and 4b show incomplete and complete versions, respectively, of a blockchain transaction adapted to provide payment and associated change for the vehicle; and

FIG. 5 shows a blockchain transaction adapted to provide a refund to a user of the vehicle.

In this illustrative scenario, we describe a method for controlling a driverless taxi via a blockchain. The use of the blockchain provides the inherent advantages provided by that technology. These advantages include a tamper proof record of events and increased security of currency exchange.

In this vehicle, we use the example of a taxi. However, the invention is not intended to be limited in this regard. The vehicle can be any IoT device or apparatus arranged for transportation of passengers and/or goods.

In our example, the taxi is an Internet of Things (IoT) device able to perform a range of possible functions such as resource-related functionality. A user's cryptographic key (PubKey) is communicated to the taxi for storage thereon or therein, in order to facilitate access. The taxi itself is capable of generating, storing, and communicating its own public and private keys, and signatures for signing blockchain transactions associated with provision of the driverless taxi service, and is able to send and receive wireless communications to users and providers of the taxi service. An IoT device is a programmable “Blockchain IOT Device (BID)” i.e. it is an internet-enabled device which is also able to monitor, interact with and publish to a blockchain network. The invention also includes a communication protocol. In a preferred embodiment, this enables communication with the resource via a software application (app).

Alice is a prospective user of a taxi service provided and managed by Bob. Alice may otherwise be referred to as a ‘user’ or ‘customer’. Bob may be referred to as a ‘resource controller’ or ‘resource operator’. Alice provides to Bob a request for a taxi service which includes journey information comprising a pick-up location, a drop-off location, and the number of passengers that would like to be picked up by a taxi. This information may be sent in any suitable form, such as a text message, email, or as a tokenised transaction on the blockchain.

The communication between Alice and Bob may be initiated and/or controlled using a software application (app) which is downloaded and installed on Alice's computing device eg smartphone, tablet, laptop etc. The smartphone may provide certain pieces of information to Bob's server. For example, it may provide information relating to Alice's current location by using a GPS capability.

Having received the information from Alice, Bob estimates the cost of the journey, for example 5 Bitcoins (BTC), and communicates this estimate to Alice by any suitable means. Bob also determines the location of the nearest taxi to Alice's pick-up location, and may choose to factor in the distance from that taxi to the pick-up location to his estimate. If Alice accepts the estimate provided by Bob, and the terms and conditions of the service (which are publically accessible prior to initiation of the service and might be stored, for example, on Bob's website or social media pages), she communicates this acceptance to Bob by any suitable means, for example by text message, email, or phone call. Any one, or all, of these communications may be hashed and stored in a publically-accessible resource e.g. a distributed hash table for future reference for example in the circumstances where a dispute regarding a quoted estimate or journey details arises. These communications could also be recorded in further blockchain transactions.

Upon receipt of Alice's acceptance, Bob instructs the taxi to generate a blockchain transaction (Tx1, a deposit transaction) which includes an output having 2-of-3 multisig address using Alice's public key, Bob's public key, and the taxi's public key. Any blockchain transaction (Tx) signed with this 2-of-3 multisig address can only be redeemed by another transaction which includes an input having unlocking script which provides of any two of the specified signatures.

Alice chooses a secret value, such as a password, string, or number sequence or any other data type, which she keeps secret. Alice generates a first blockchain transaction, hereafter referred to as a “deposit transaction”, comprising an output which spends an amount equal to Bob's estimate for the cost of the journey—in this example, 5 BTC. Alice signs transaction Tx1 with her digital signature, locks the transaction using a hash of her secret value, and sends the transaction to the multisig address generated by the taxi. Transaction Tx1 is broadcast to the blockchain.

The 5 BTC associated with the output of this transaction can only be spent by providing an unlocking script (in another transaction) which includes both Alice's private cryptographic key and two of the three signatures corresponding to the multisig address—in this example, any two of: Alice's signature; Bob's signature; and the taxi's signature. In this way, the 5 BTC of the deposit transaction are not spendable by Bob without Alice's key, and are not spendable by Alice because she is only able to provide one of the three signatures required. An example of the deposit transaction, Tx1, described above is shown in FIG. 1.

Bob then instructs the taxi to collect Alice and transport her to her destination. Bob may send the journey information to the taxi by any suitable means, such as via a software application capable of communicating with the taxi, or he may choose to create a tokenised blockchain transaction, hereafter referred to as “token transaction”, capable of communicating journey-related information. The token transaction comprises an underlying value, which is usually chosen to be as small as possible because the value is not related to the purpose of the token transaction, and information embedded in the token transaction metadata. This embedded information contains either the journey information itself, or a pointer to the information, or a hashed version of the information or the pointer thereto. The pointer may take the form of a URL or a Torrent link directing the taxi to an online resource containing the journey information. An example of the token transaction is shown in FIG. 2, where the metadata is shown to contain a reference to “mess₁” in the redeem script of the transaction output: “mess₁” is a message generated by Bob which contains the journey information.

Bob then sends a message to the taxi, by any suitable means, upon confirmation of the token transaction's validation instructing the taxi to monitor the blockchain for the token transaction. The taxi uses its private cryptographic key to claim the output of the token transaction, thereby gaining access to the journey information sent by Bob.

Validation of one or more transactions includes checking that those transactions satisfy, among other criteria, syntactical correctness rules inherent in the blockchain code.

The taxi then proceeds to collect Alice at the pick-up location. The taxi may require Alice to send a message signed with her private key to unlock the taxi door. The taxi may use appropriate detection equipment, such as an infrared camera, to detect the number of passengers that enter the car and decide whether or not to provide the service depending on how that number compares to the number initially provided by Alice: for example if Alice provided journey information stating that there was to be only one passenger, and two or more passengers enter the taxi, the taxi may be configured to refuse to carry out the journey.

The taxi may ask Alice to confirm any of the journey information, such as the accuracy of the pick-up location and the destination, and any messages sent between Alice and the taxi may be hashed and stored in a DHT for future reference, as described above. The taxi may be configured only to commence the journey once one or more such confirmation messages are received, and may be further configured to prevent opening of the doors after arrival at the destination until further confirmation messages are received.

The taxi then prepares up to three transactions: a return transaction; a proposed transaction, and a refund transaction. In one or more embodiments, the proposed transaction is the only transaction which is essential to the operation of the present invention. The taxi may generate one or more of these transactions upon completion of the journey.

The return transaction is configured to return the underlying value of the token transaction (shown in FIG. 2 to be a “few Satoshis”) to Bob. An example of this return transaction can be seen in FIG. 3, which shows the “few Satoshis” in the output field of the transaction. However, even if Bob chooses to send the journey information in the form of a token transaction, he may not require or instruct the taxi to return the underlying value.

The proposed transaction, an example of which is shown in FIG. 4a , may be referred to as an incomplete transaction, or a transaction template. Upon completion of the journey, the taxi generates a proposed transaction having two inputs and at least one output. The first input is signed using a cryptographic signature and a public key associated with the taxi using sighash flag SIGHASH_ALL|SIGHASH_ANYONECANPAY, while the second input is signed only with a signature associated with the taxi. The first output corresponds to a payment to Bob for providing the service (in this case, the service actually cost only 3 BTC), and the second output (if required) corresponds to change for the service equal to the difference between the deposit transaction amount and the first output of the proposed transaction (in this case, 5 BTC deposit−3 BTC actual cost=2 BTC change) which is to be sent to Alice.

The purpose of the first input, signed using the above sighash flag, is to prevent Alice from modifying the output or outputs of the proposed transaction (by, for example, changing the value of the first output to 0 BTC for a free taxi ride) but allowing her to modify the second input in order to add necessary information. In this case, this necessary information is: Alice's signature, the redeem script from the deposit transaction, and Alice's secret value. These three items must be added to the signature script of the second input in order to successfully unlock the proposed transaction, paying Bob the 3 BTC for the service. These three items are shown in FIG. 4b , the completed version of the proposed transaction which Alice returns to the taxi.

The taxi then submits this transaction to the Blockchain and may be configured to unlock and/or open the doors once the transaction is either validated or verified.

If Alice refuses to disclose her secret value, then by virtue of the deposit transaction being locked with a 2-of-3 multi-signature locking script, Bob may choose not to use his and/or the taxi's private keys to allow the 5 BTC of Alice's funds to be redeemed. Therefore, because the 5 BTC is irredeemable to anyone until Alice makes her secret value publicly known, Alice is motivated to be conduct transactions in the service honestly.

The taxi may generate a refund transaction allowing Alice to redeem the output of the deposit transaction if she decides not to use the service. This transaction is presented to Alice at the pick-up location. To regain her 5 BTC, both the taxi and Alice must present their signatures to the refund transaction's unlocking script. Instead of allowing the full 5 BTC amount to be refunded, Bob's terms and conditions may stipulated a subtracted fee to be paid to a public key associated with either the taxi or Bob, which would alter the refund transaction to have two outputs: the first output corresponding to a refund redeemable by Alice of 5 BTC minus the cancellation fee; and the second output corresponding to the fee redeemable by either the taxi or Bob. The taxi monitors the Blockchain and, before signing a proposed transaction, checks that no corresponding refund transaction has been spent.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The word “comprising” and “comprises”, and the like, does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. In the present specification, “comprises” means “includes or consists of” and “comprising” means “including or consisting of”. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. 

1. A blockchain-implemented method for controlling the use of an internet-enabled resource comprising the steps of: providing a first blockchain transaction comprising at least one output which is redeemable only by provision of at least: a secret value selected by a user; and a signature associated with a resource provider; sending use-related information to the resource; generating a second blockchain transaction requesting at least the secret value; and modifying the second blockchain transaction to include the secret value.
 2. A method according to claim 1, wherein the resource is a vehicle and the use-related information comprises information related to a journey.
 3. A method according to either claim 2 wherein the use-related information is sent by the resource provider in the form of a tokenised third blockchain transaction comprising either the information or a location thereof.
 4. A method according to claim 3, further comprising a step of generating a fourth blockchain transaction comprising at least one output redeemable to return an amount of cryptocurrency underlying the tokenised third blockchain transaction to the resource provider.
 5. A method according to claim 1, wherein the second blockchain transaction is generated by the resource and the modification is performed by the user.
 6. A method according to claim 1, wherein the second blockchain transaction comprises a first output relating to payable first asset transferrable to the resource provider and a second output relating to a second asset transferrable to the user.
 7. A method according to claim 1, wherein the second blockchain transaction comprises preventing means for preventing at least one output of the second blockchain transaction from being modified by the user.
 8. A method according to claim 6, wherein the preventing means takes the form of a securing input to the second blockchain transaction comprising the sighash flag SIGHASH_ALL|SIGHASH_ANYONECANPAY.
 9. A method according to claim 8 wherein the securing input comprises an amount of cryptocurrency provided by at least one of the resource provider and an electronic wallet associated with the resource.
 10. A method according to claim 1, further comprising a step of generating a fifth blockchain transaction comprising at least one output redeemable to refund an amount of cryptocurrency associated with the first blockchain transaction responsive to non-use of the resource.
 11. A method according to claim 1, further comprising the step of unlocking the resource in response to validation of modification of the second blockchain transaction.
 12. A method according to claim 1, further comprising the step of a user sending at least one confirmation message confirming accuracy of the use-related information, hashing said message and storing said hashed message in a distributed hash table.
 13. A method according to claim 1, further comprising the step of hashing the use-related information and storing said hashed information in a distributed hash table.
 14. A method according to claim 1, further comprising the step of determining a number of users present in the resource and allowing or disallowing provision of the resource dependent on said number.
 15. A method according to claim 1, wherein the resource is a driverless car.
 16. A system arranged to perform the method according to claim
 1. 